The present invention relates generally to valves and more specifically to valves for use in a pneumatic brake system for rail vehicles.
Valves, for example, angle cocks in the rail industry, is illustrated in FIG. 1, generally includes a body 1 and a valve element 3, illustrated as a ball, between seats 2 within the body 1. A stem 5 is received within the ball 3 and includes a key 4. Washer 6 is provided on the stem 5 as are O-ring seal 7. A gasket 8 is positioned between the body 1 and a cover 9 which is secured to the body 1 by fastener 10. The handle 14 is secured to the key 4 by socket 12 and pin 11. Pin 13 connects the pivotal portion of the handle 14 to the socket 12. Rings 15 and 16 are secured to the threaded portion of the housing 1 by nut 17.
The stem 5 included a perturbance 18 which was received in slot 19 of valve element 3. The connection can best be seen in FIG. 2. Generally, the valve element or ball 3 is made of brass or aluminum and the stem 5 or perturbance 18 is made of steel. In the field, sometimes the valve element 3 gets stuck. In order to gain appropriate leverage, a pipe is usually fitted over the handle 14 to create a greater lever or moment. Depending upon the age of the valve and what makes it stick, the stem 5 may break at perturbance 18. The operator would not know that the valve elements have not moved since the connection of stem 5 to ball 3 is interior of the housing.
A similar valve structure for the dirt collector and cut-off cock of a railroad pneumatic brake system is illustrated in FIG. 3. The body 21 receives seats 22 and valve or ball element 23. A stem 25 with a key 24 is received in the valve element 23. Washer 26 and O-rings 27 are received on the stem 25. A gasket 28 is a seal between the cover 29 and the body 21 and is held thereto by fastener 30. The handle 31 is secured to the key 24 of the stem 25 by pin 31. A gasket 33 is between the bowl 35 and the body 21 and is secured thereto by fastener 36 and nut 37. A valve 34 is provided in the bowl 35. The valve element 23 and stem 25 are connected by perturbance 38 of the stem 25 in recess 39 in the valve element 23. The same problem occurs where excess force will cause a breakage of the perturbance 38 which is interior the body 21. Although the use of metal handles, stems and valve element increase longevity of the individual elements, an inherent weak point at the junction of the stem to the ball. Also, the metal pieces are not inexpensive.
The present invention is a valve including a body, a valve element stem extending from the valve element exterior of the body and a handle connected to the stem for moving the valve element. The stem and valve element are a unitary structure and the stem includes a weakened section adjacent the exterior of the body. Preferably, the unitary structure is a one-piece molded plastic structure. The body and the handle may be metal. The weakened section is exterior of the body and may be a circumferential groove. The stem includes a key to which the handle is connected and the weakened section is between the key and the valve element. The valve element may be a ball and may be part of an angle cock, dirt collector and cut-off valve or a retainer valve. The plastic unitary structure may be fiberglass re-enforced. It may also be made of high strength, high temperature and low friction plastic material.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.